Lise Sarfati's best shot

My goal is to capture a moment in people's everyday life. This photograph is of a teenage girl called Sloane, whom I met in Oakland, California, in 2003. I was on a road trip across America, doing a series called La Vie Nouvelle, or The New Life, about middle-class adolescent girls in small provincial cities. I wanted to photograph them in free situations - at home, or in convenience stores. Most of the girls I met in malls or schools, but Sloane was the friend of a friend. I don't know exactly how old she was - somewhere between 15 and 17.

This is the house Sloane shared with her mother and sister. We were in a sort of loft, the kitchen-diner. The door behind her leads to her bedroom, which was actually a safe. You can see in the picture, through the open door, that it had no windows. But she was not unhappy with it; in fact, the room was very trendy.

I didn't hang out with any of the girls for too long. If I spent too much time with them I would create a moment that didn't exist. So I just watched what Sloane was doing, and when I saw something I liked I stopped her where she was. Then I shot her with a Leica 35mm camera, with a 35mm lens, and just natural light, as always.

What interests me is the way people regard themselves. When we are 15, we all feel as if we are beginning to become somebody else. When I first met Sloane she was very shy, and she was wearing a wig. She seemed already to be creating a new personality for herself. She was very pretty, but she looked like she was hiding herself. She didn't like her body much: she thought she was too fat. Her surroundings were all very melodramatic - she had an almost religious way about her.

I like the fact that this image is quite mysterious. I can look back at it, years later, and notice new things that I had not seen.

Curriculum vitae

Born: Oran, Algeria, 1958.

Studied: "I taught myself."

Inspirations: "Most of my influences are literary, but among photographers it would be Philip-Lorca diCorcia, Nan Goldin and Cindy Sherman."

High point: "Working on this project, La Vie Nouvelle."

Low point: "Spending 10 years in Russia. I was a little crazy at the time, and I wanted to find the most extreme situations I could. I loved the experience, but it was like a descent into hell."

Pet hate: "The slow times between jobs."

Dream subject: "To continue this series in Japan."

Acta Est, a book of photographs by Lise Sarfati, is published by Phaidon Press.